The primary objective of the Biostatistics, Epidemiology and Administrative Core is to maintain a high level of statistical and competency and uniform standards of measurements for the research project and to administer the overall program project. This core will perform data management and analysis for the projects and other cores. In addition, it will be responsible for the determinants of bone mass, anthropometrics, dietary intake of nutrients, physical activity levels and muscle strength, as neede by the five projects. Data management will be performed primarily with a microcomputer system designed for this purpose. This permits efficient fil generation for transmitting to the larger mainframe computers for data analysis using SAS. Research assistants performing anthropometric measurements will be retrained regularly. Individual dietary intake of calcium and caffeine nutrients will be quantified by the use of food frequency questionnaires. Self-reports of alcohol intake and cigarette consumption will be obtained. Two different questionnaires will be used to illicit activity levels from adults and from children. A portable dynamometer will be used to measure lower extremity strength. Bone mass measurements for all projects will be performed by experienced, technicians, using single and dual photon as well as x-ray absorptiometry for radial, vertebral, hip and total body scans. Quality control experiments will be performed regularly.